Thermoplastic polyester resins have been used in a wide variety of fields such as mechanical components of machines, electric and electronic components, and automobile components because of its excellent injection molding adaptability, mechanical properties, and other features.
However, the thermoplastic polyester resins are inflammable by nature, and when the thermoplastic polyester resins are used as an industrial material for machine mechanical components, electric and electronic components, and automobile components, safety to the flame, namely, high flame retardancy as represented by V-0 in the UL-94 standard is required in many cases in addition to the balance between chemical and physical properties generally required in the art. When the thermoplastic polyester resins are used in the environment where electric current is applied, safety to the tracking failure caused by ignition by resin decomposition and carbonization by electric discharge, namely, tracking resistance is required. Accordingly, high tracking resistance as represented by the CTI grade 0 in the IEC 60112 standard is required in many cases, and in particular, higher tracking resistance is demanded due to recent focus of attention on electric vehicle in view of the environmental consciousness.
The method commonly used for providing the thermoplastic polyester resin with tracking resistance include incorporation of an agent for improving the electric properties such as organic phosphinic acid compound or melamine cyanurate.
In addition, a flame retardant resin composition having improved electric properties comprising a polyalkylene terephthalate resin, vinyl resin, or phosphate ester and a salt of a triazine compound and cyanuric acid or isocyanuric acid has been proposed as means for improving the flame retardancy and the electric properties of the thermoplastic polyester resin (see Patent Document 1). However, this proposal had the problem that the flame retardancy and the electric properties were still insufficient.
A flame retardant resin composition having improved electric properties comprising a base resin, a halogen flame retardant, an organic phosphinic acid or its salt, a flame retardant aid, and an aid for improving the electric properties such as melamine cyanurate is also proposed as another means for improving the flame retardancy and the electric properties (see Patent Document 2). This proposal, however, had the problem that the tracking resistance was still insufficient. In addition, the resin composition containing a halogen flame retardant is associated with the risk of the generation of toxic dioxin in its burning, and there is a demand for a flame retardant resin composition containing a non-halogen flame retardant.
The flame retardant resin compositions containing a non-halogen flame retardant that have been proposed include a resin composition prepared by blending a thermoplastic resin such as a polybuthylene terephthalate resin, phosphate ester compound, a thermoplastic resin such as a methacrylate resin (see Patent Document 3); a resin composition containing a polybuthylene terephthalate resin, a thermoplastic resin such as a methacrylate resin, a phosphate ester flame retardant, at least one metal salt selected from alkali metal salt and alkaline earth metal salt, and a salt of a triazine compound and cyanuric or isocyanuric acid (see Patent Document 4); a flame retardant resin composition simultaneously having mechanical properties and flame retardancy prepared by using a non-halogen flame retardant, for example, a resin composition containing a thermoplastic polyester resin, a phosphazene flame retardant, and a phosphate ester flame retardant, and a nitrogen compound such as melamine-cyanuric acid adduct (see Patent Document 5); and a resin composition prepared by blending a phosphor-containing flame-retardant comprising a particular aromatic phosphate ester compound and a phosphate ester compound having a molecular weight of 100 to 500, and a flame-retarding aid such as nitrogen compound based flame retardant to a thermoplastic polyester resin (see Patent Document 6). However, the resin compositions described in the Patent Document 3 and Patent Document 4 had the problem in the insufficient tracking resistance while they were capable of improving the problem of low warpage and the like of the molded articles. In addition, the resin compositions described in the Patent Document 5 and Patent Document 6 also had the problem of insufficient tracking resistance.